1. Field of the Invention
The invention relates to an apparatus for separating mixed substances of differing flowabilities, in particular in the processing of foodstuffs, the foodstuff to be processed being pressed, by means of an elastic, endless presser belt, against a hollow separating drum driven to rotate and having a perforated circumferential surface, for which purpose said presser belt is guided while enclosing part of said circumferential surface of said hollow drum and forming therewith a pressure zone as well as a draw-in wedge for said substances to be processed, and pressure exerting means are arranged for pressing said presser belt against said separating drum.
With this kind of device, generally referred to as separator, substances and mixtures of substances can be subjected to a separating process by which a separation of substances of differing flowabilities takes place. Thus, assisted by this process, the possibility exists to separate e.g. fish flesh from bones and skin, various kinds of meat from bones, tendons, ligaments, sinews and skins, fruit e.g. apples from skin/peel, pits, stems stems etc., butter and cheese from packaging material--e.g. for unpacking incorrect packaging--and much more.
This kind of processing shows that every substance to be treated can only be optimally processed according to its consistency and mixture by using certain variables or setting parameters, this statement aiming particularly at characteristics of quality and rather less at those of quantity, i.e. yield. If upon optimizing quality it is hitherto determined that this, for example, causes reduced yield, it is either accepted as such or the remainder of the substance to be processed is subjected to a second separating treatment according to other parameters. By this manner of procedure, it is also possible to obtain specific products having different levels of quality.
2. Prior Art
For the last-mentioned possiblity, a press-passing machine is provided, which can be taken from DE-PS 35 16 623. This machine is designed for removing the flesh of fish by separating it from bones and comprises for the purpose of producing different levels of qualtity a presser belt, which communicates with two separating drums positioned one behind the other. Each separating drum is associated with an individual pressure exerting system, so that the working parameters, such as pressing force, diameter of the holes in the separating drum, and drum diameter, can be defined and designed differently. The yield of meat parts of varying levels of quality is obtained through utilisation of the circumstance that the meat of less quality lies under the skin and is thus more strongly connected to the skin, so that the detachment thereof requires a higher pressure of the presser belt against the drum than the detachment of the remaining meat portions.
Disadvantageous in this configuration is the use of two drums, which are very costly in respect of production, positioning (support) and drive, as well as the additional straining of the presser belt, which is already subject to a high degree of wear. Furthermore, due to this system the hardness and consistency of the presser belt principally effects both separating drums in the same manner, i.e. mutually.